Temperature dependence of orthogonal pinning of two ferromagnetic layers in a synthetic antiferromagnetic TMR device

A method for pinning synthetic antiferromagnet (SAF) based spin-valves is presented, which allows pinning to be established perpendicular to the setting field H. As the SAF (AP1/Ru/AP2) magnetizes, its layer moments undergo a spin-flop transition for a magnetic field H = HSF, and align with H for H = HSat. The magnetization of layer AP1 is perpendicular to H for a field H = HGold. This field corresponds to the maximum GMR on HSF < H < HSat for an unpinned SAF spin-valve. The spin-flop handedness is found to be temperature dependent. Both the coupling strength between AP1 and AP2 in the annealed SAF spin-valve and HGold of as-deposited SPV was found to decreases with the temperature. The observed phenomenon can be explained by the temperature dependence of long-range RKKY interaction through Ru layer.